POWER GENERATED BY A
TOPSPIN VS. A SLICE
Ali Kazmi
April 30, 2012
2
Breaking Down a Shot
Every human motion is driven by the synergistic action of the basic
biomechanical unit.
• The basic biomechanical unit
consists of a pair of mutually
antagonistic muscles that
produce a common muscular
torque in the same joint
• In tennis, the most obvious
example is the biceps-triceps
pair (pictured)
from Ivancevic et al. (2008)
An example of the basic mechanical unit
3
Breaking Down a Shot
The three components of the kinetic chain (nervous,
muscular, and skeletal systems) all work together to produce
movement.
Breaking Down a Shot
4
The standard forehand has two main phases: (i) preparation or
“loading,” and (ii) hitting the ball.
Preparation or “Loading”
• Includes two simultaneous actions:
stepping into the right position with the
left leg forward (if right-handed) and
lifting the racquet above the shoulders
• Muscles involved: right deltoideus and
biceps
Hitting the Ball
• Includes three main movements:
• Right hip rotation towards the ball with feet
still on the ground (muscles involved: right
gluteus maximus and medius muscles)
• Arm swing of the racquet (Muscles involved:
right pectoralis major, deltoideus, and biceps)
• To create topsin, a slight twist of the wrist to
brush over the ball (muscles involved: right
palmar flexors)
Not pictured: gluteus maximus
5
Breaking Down a Shot
The topspin is a forehand shot generated hitting the ball with an upand-forward force that causes the ball to drop.
What is “Topspin”?
• “Topspin” refers to the property of a ball
that rotates as if rolling in the same
direction as its velocity.
• Topspin inflicts a downward force that
causes the ball to drop due to its
interaction with the air (called the Magnus
effect
Use in Tennis
• Topspin provides the player an
increased margin of error because the
ball hits the ground quicker, and so can
rise higher above the net
• The racquet should face below the
direction the ball is moving, and brush
up against the back of the ball
6
Breaking Down a Shot
The splice is a forehand shot that utilizes “backspin” to cause an upward
force that lifts the ball.
What is “Backspin”?
• “Backspin” refers to the property of a
ball that rotates as if rolling in a
direction opposite to its velocity
• An upward force is applied to the ball
that lifts the ball (also due to the
Magnus effect)
Use in Tennis
• A splice is useful for defensive shots
because the ball takes a longer time to
reach the opponent, giving the player
more time
• Backspin shots also tend to bounce
lower when the reach the opposite
court.
7
Power Generation in a Topspin Stroke
Instantaneous Power = Change in Energy
• Initial Kinetic Energy
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m= 0.057kg
X-velocity= 0.937m/s
Y-velocity = 0.912m/s
Overall velocity= 1.31m/s
g=10m/s2
h= 0.9213m
KE= ½*m*v2 =0.050J
PE= mgh= 0.53
Total Energy= 0.58
• Final Kinetic Energy
•
•
•
•
•
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•
•
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m= 0.057kg
X-velocity= 28.973m/s
Y-velocity = 2.517m/s
Overall velocity= 29.08m/s
g=10m/s2
h= .9213m
KE= ½*m*v2= 24.1J
PE=mgh= 0.53J
Total Energy= 24.6J
Power Generated= 24.02W
Power Analysis
8
Power Generation in a Slice
Instantaneous Power = Change in Energy
• Initial Kinetic Energy
•
•
•
•
•
•
•
•
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m= 0.057kg
X-velocity= 0.863m/s
Y-velocity = 0.814m/s
Overall velocity= 1.19m/s
g=10m/s2
h= 1.051m
KE= ½*m*v2 =0.040J
PE= mgh= 0.60J
Total Energy= 0.64J
• Final Kinetic Energy
•
•
•
•
•
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•
•
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m= 0.057kg
X-velocity= 24.096m/s
Y-velocity = 2.170m/s
Overall velocity= 24.2m/s
g=10m/s2
h= 1.051m
KE= ½*m*v2= 16.7J
PE=mgh= 0.60J
Total Energy= 17.3J
Power Generated= 16.66W
Power Analysis
9
Future Directions
• Further detailed analysis of impact rotation kinetic energy
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•
•
•
changes
Energy transfer measurements
Strategic considerations
Impact of elasticity of strings of racquet
Frequency of usage of different types of shots and
success/failure ratios
10
References
• Elliott, B. "Biomechanics and Tennis." British Journal of Sports
Medicine 40.5 (2006): 392-96. Print.
• Ivancevic, T. “Biomechanical Analysis of Shots and Ball Motion
in Tennis and the Analogy with Handball Throws.” Physical
Education and Sport 6.1 (2008): 51-66. Print